Development of Sarcocystis in mule deer transmitted through dogs and coyotes

Tissues from 13 experimentally inoculated mule deer (Odocoileus hemionus) from Oregon, studied by G. Hudkins and T. P. Kistner in 1976 and L. D. Koller, T. P. Kistner, and G. Hudkins in 1977, were reexamined. The following additional information on Sarcocystis hemionilatrantis was obtained. Two types of meronts were found in deer necropsied between 29 and 41 days postinoculation (DPI). Type 1 meronts were in capillaries in adrenal glands, kidney, lymph node, lung, choroid plexi, and spleen; meronts were 20.5 × 13.5 μm (14−32 × 10−20 μm; n = 26) and contained 20 to 35 nuclei. Type 2 meronts were found in macrophages in muscular tissues; these meronts were 20 × 14 μm (10−35 × 7−19 μm; n = 7) and contained 10 to 60 merozoites. Sarcocysts were seen in three deer at 63, 65, and 90 DPI. At 63 and 65 DPI sarcocysts were immature and their walls were thin (< 1 μm) and smooth. At 90 DPI, sarcocysts were up to 525 μm long and 50 μm wide; the sarcocyst wall was 1 to 2 μm thick and cross striated. In the same deer another type of mature sarcocyst was also seen; sarcocysts were up to 825 μm long, the walls were 2 to 4 μm thick and lacked cross striations. Two additional 3-day-old deer were inoculated orally with sporocysts from the feces of a dog fed meat from a mule deer from Montana naturally infected with Sarcocystis sp. Deer No. 1, fed 107 sporocysts, was killed at 14 DPI and deer No. 2, fed 5 × 106 sporocysts, was killed at 24 DPI. At 14 DPI, meronts were found in capillaries and arteries in the lung, heart, and spleen; the meronts were 26.5 × 20 μm (14−39 × 14−25 μm; n = 31) and contained up to 100 nuclei. At 24 DPI, intravascular meronts were found in the spinal cord, hepatic lymph node, kidney, thyroid gland, and mesenteric lymph node. In addition, meronts were found in macrophages in muscular tissues; these meronts were 16 × 10 μm (10−28 × 7−14 μm; n = 10) and contained up to 40 nuclei.